P025 HLA antibody targets: Pre-transplant, post-transplant, post-graft loss

Abstract

Aim It has often been noticed that the most frequent target of donor-specific HLA antibodies (DSA) in post-transplant monitoring are DQ antigens, at a rate significantly higher than that observed in patients awaiting transplant. This study is an attempt to quantify that observation. Methods From 2012 to 2017 sera from patients who had received or were waiting to receive a 1st or 2nd second kidney transplant were tested using the LABScreen Single Antigen kit. To avoid counting patients twice within a stage (pre-1st transplant, post-transplant, relisted for 2nd transplant) patients were evaluated for this study only on their most recent serum within each stage. 5896 patients pre-1st transplant (3458 males, 2438 females), 2626 patients who received post-transplant testing for DSA, and 754 patients who were relisted for a 2nd transplant were evaluated. As reliable transfusion and pregnancy information was unavailable for most pre-transplant patients, the difference between male and female sensitization rates was used as a surrogate for the different sensitizing effects of transfusion versus pregnancy in this stage. Results Sensitization to any HLA was 14% in pre-transplant males, 38% in pre-transplant females, 15% in post-transplant monitoring (but only evaluated for DSA), and 71% in patients relisted for a second transplant. Males and females pre-first transplant show significant differences in antibodies against class II, and also against HLA-B and to a lesser extent HLA-C. Post-transplant DSA shows a very high rate of antibodies against HLA-DQ, and relatively little against class I. Patients relisted for a second transplant show extensive antibody production against antigens of all loci, especially HLA-A, B, DRB1 and DQ. Conclusions The three major sources of sensitization to HLA, transfusion, pregnancy and transplantation, show different rates of sensitization to different HLA loci. Among HLA antibody producers, antibodies to DQ are 2–3 times more frequent as DSA than they are as pre-transplant antibody targets. Download : Download high-res image (215KB) Download : Download full-size image